Understanding of underlying risk, predisposing factors, and effective treatments with high-safety profile for breastfeeding mothers with postpartum depression continues to evolve.
As investigation into neuroinflammatory models of depression becomes more the focus of mainstream medicine, research into pathological patterns of immune adaptation in late pregnancy and postpartum has begun to emerge in the literature.
Alternatives to medication are highly sought after by this patient population, and these two present appealing considerations:
a. natural agents
- probiotics
- melatonin and tryptophan
- omega-3 fatty acids
- folate
- curcumin
b. behavioral interventions
- dietary modification
- exercise
- mindfulness meditation
- cranial electrical stimulation
These three are also addressed:
- inflammatory lifestyle factors
- appropriate diagnostics
- environmental modification
This article discusses neuroinflammatory models of postpartum depression.
As with the rising incidence of mental illness and associated disability, postpartum depression rates continue to escalate, commanding the attention of providers who care for women of reproductive age.
There is an urgent need to investigate the underlying contributors and etiologies of postpartum depression, anxiety, and psychosis and to create practice algorithms that guide clinicians in the process of ruling out alternative explanations for a patient’s postpartum psychiatric complaints and considering non-pharmaceutical interventions. Treatment data and longitudinal data in lactating women and in the postpartum population generally are lacking. When it comes to treatment data, there is insufficient information on:
- antidepressant
- mood stabilizer
- benzodiazepine
- antipsychotic medications
To support this exploration, this article will:
- discuss current theories proclaiming inflammationas a driver of postpartum symptomatology
- address proposed biomedical screening for new-onset postpartum mood and anxiety symptoms
- discuss as of yet theoretical applications of lifestyle changes and nutrients that could be applied to buffer inflammatory responses and considered as preventive strategies
Today’s pregnancies are not those of our ancestors.
We have ever-inflating incidences of maternal and infant mortality and morbidity, particularly in America.
The changes in chronic illness in our pediatric population cannot be accounted for by Mendelian genetics, and we must look to our environment for its role in adverse epigenetic effects.
Today’s mother-to-be suffers from a toxic burden through everyday exposures, and there is reason to believe that these largely unstudied exposures are cumulative in their risk.
Additives and industrial chemical exposures all bioaccumulate in the very top of the food chain, the fetus. Some of these additives include:
- dyes
- preservatives in prenatal vitamins
- metals
- adjuvants in vaccines
Industrial chemicals include those found in:
- cosmetics
- furniture
- paints
- cars
- pollution
These factors conspire to modulate endocrine and immune responses while simultaneously rendering the body less capable of managing and supporting metabolic processes of detoxification.
This is known as oxidative stress, or the inability of the products of aerobic respiration to be effectively neutralized by endogenous antioxidant agents prior to causing damage to cellular machinery and membranes.
Environmental toxic exposures include:
a. pesticides(most notably glyphosate)
b. industrial chemicals
- polybrominated diphenyl ether (PDBE) flame retardants
- phthalates
- bisphenol A (BPA)
c. neurotoxic metals
d. carcinogens(e.g.,. dioxins)
With 80,000 registered agents in the Toxic Substances Inventory, a mere 200 have been studied for human safety parameters.
An important case series supported by the Environmental Working Group and the Red Cross examined umbilical cords, identifying 287 toxic chemicals, 217 of which are known neurotoxins.
PDBE and BPA have been associated with adverse cognitive, endocrine, and motor outcomes in children, and while ubiquitous, may represent a modifiable exposure in our immediate environment.
Between the years 1948 and 1971, treatment of pregnant women treated with a synthetic estrogen and diethylstilbestrol (DES), demonstrated epigenetically driven reproductive effects two generations later, leading to its ban in 1971.
Similarly, in a study published in 2006 by the journal Endocrinology, authors Matthew D. Anway and Michael K. Skinner have looked at germ cell inheritance of chronic disease phenotypes (tumors, kidney disease, immune dysfunction) in fourth-generation rats born of pesticide-exposed ancestors, demonstrating that these non-DNA-sequence-related phenotypes could be passed down.
Their research serves to sound the alarm on two things:
- understudied environmental toxins
- the role of environmental toxins in consideration of pregnancy exposures
A recent report on the potential harm associated with the most ubiquitously applied pesticide, glyphosate, typically applied to ‘roundup-ready’ genetically modified crops (soy, corn, sugar beets, etc.) discusses the potential role of this chemical in depleting tryptophan and altering gut flora functioning related to the pesticide’s bactericidal effects on gut microbiota. Alteration of microbes in gut ecology may have deleterious effects independent of the depletion of this essential amino acid.
The role of healthy gut microbial balance will be discussed in the following, but the integrity of colonic enterocytes rely on healthy balance of bacteria and fungi for:
- nutrient absorption
- vitamin production
- immune protection
These exposures may be driving inflammatory responses and perturbations of the antenatal immune system in ways that deleteriously affect the fetus and put the mother at greater risk for postpartum mood pathology.
The experience of pregnancy is one that draws heavily on a woman’s native nutrient stores and involves fluctuations in hormone levels and immunologic parameters.
The anabolic state of pregnancy demands a synergy of nutrients not only to nourish the growing fetus but also to support the tissues of reproduction (mammary, placental) and metabolism.
Some theorize that the relative deficiencies of certain critical nutrients may make some women more vulnerable to postpartum psychiatric symptoms.
A study published in 2000 by the Journal of the American Dietetic Association, with Jacqueline Borah Giddens as lead author, found that majority of pregnant American women were consuming below recommended amounts of:
- iron
- zinc
- calcium
- magnesium
- folate
- vitamins D and E
According to the study, selenium supplementation may protect against the development of postpartum depression.
In addition, elements of our modern diet, including high sugar (fructose) content and trans fats rendered from heat-labile vegetable oils, contribute to free radical production and a drive on behalf of the body, to manage these perceived sources of inflammation.
Two studies (both published by The American Journal of Psychiatry) have raised questions about the role of foods such as gluten and dairy in the development of postpartum depression and psychosis, finding that plasma/cerebrospinal fluid morphine-like fragments derived from casein and gluten may have an association with maternal psychopathology (1984 study with Leif H. Lindstrom as lead author) and, potentially, mental illness in the child (2012 study with Hakan Karlsson as lead author).
Several years of preliminary work have focused on the premise that these affected women experience suppression of the hypothalamic-pituitary axis (free cortisol-releasing hormone and corticotropin-releasing hormone) more severely and extensively than ‘normal’ controls and that postpartum blues may represent the activation of inflammatory response system.
In states of relative hypocortisolemia (or low hypothalamic activity), the following are more likely:
- inflammation
- infection
- autoimmunity
Specifically, studies have noted that macrophages are activated and TH1 (Type 1 T helper) cells are suppressed, suggesting that this aberrant immune response may be a significant driving force in the presentation of altered mood states.
A relatively recent discovery is the psychoneuroimmunologic bridge - the kynurenine pathway.
In animal and clinical research, the kynurenine-to-tryptophan ([Kyn]/[Trp]) ratio has been used as a marker of inflammation correlated with postpartum depressive behaviors and states.
Inflammatory messengers, or cytokines IL6 (Interleukin 6) and TNF-alpha (tumor necrosis factor alpha), have been demonstrated to be elevated in the cerebrospinal fluid of women at the time of their childbirth, who then presented with depression at 6 weeks postpartum.
Similarly, elevated levels of IL-1B (Interleukin-1 beta) predicted depressive symptoms at 1 month postpartum.
In the non-pregnant population, inflammatory underpinnings of depressive illness (cytokines, chemokines, reactive proteins, adhesion molecules) have been well-established, and anti-inflammatory interventions have been explored.
Among other disruptive effects, these inflammatory agents induce the enzyme indoleamine 2,3-dioxygenase (IDO), which ‘steals’ tryptophan in the production of kynurenine, resulting in a net decrease of serotonin.
Cortical cells appear to specifically convert kynurenine to kynurenic acid, which acts to decrease activity through acetylcholine antagonism.
Meanwhile, in the amygdala, primitive impulses may go unchecked secondary to N-methyl-D-aspartate (NMDA) receptor agonism by quinolinic acid.
A brilliant review of this theory proposes that this sequence of unfortunate events may account for the intrusive violent images and impulses that often accompany postpartum mental pathology.
The picture below shows how metabolism of tryptophan is skewed by stress and inflammation:
A diagram with arrows pointing straight downwards and two diagonally and originate from the word ‘tryptophan’ In addition, an excellent review of the literature highlights seven studies examining postpartum depression and its association with inflammatory modulators, the best studied of which are IL1, IL6, c-reactive protein (CRP), and TNF-alpha, further supporting the association between mood states and inflammation.
Macrophage-driven cytokine production is an area of ongoing investigation in this population.
These models remain theoretical, and so are serotonergic theories of depression; hence, the consideration of individualized screening and low-risk interventions is appropriate.
The monoamine hypothesis of depression and anxiety and associated pharmacologic interventions have fallen short of expected treatment responses, and one reason for this may be the underlying etiology continues largely unabated in treated patients.
Assessing for individual parameters of a highly heterogeneous diagnosis serves to optimize benefit and minimize risk.
Screening for the following markers is recommended to assess for drivers of inflammation:
- homocysteine (Hcy)
- C-reactive protein (CRP)
- fasting insulin/glucose
- hemoglobin A1C (HbA1C)
- Vitamin D 25 OH and 1,25 (25-hydroxyvitamin D and 1,25-dihydroxyvitamin D)
- methylmalonic acid (MMA)
- TSH (thyroid-stimulating hormone), free T3 (triiodothyronine), free T4 (thyroxine), and thyroid antibodies
- celiac panel
- methylenetetrahydrofolate reductase (MTHFR) genetic profile
Consideration of alternative treatment and non-medication alternatives is discussed in a review by Kelly Brogan and published in 2013 by the journal Psychiatric Clinics of North America; however, the following will focus on theoretical anti-inflammatory interventions.
These two may serve to protect the interests of the mother and the growing infant:
- targeted lifestyle recommendations around minimization of personal care products, home, and food-based toxins
- a focus on whole, organic, unprocessed food
It is recommended that women:
1. Filter their air and water.
2. Purchase products free of known carcinogens and endocrine disruptors, such as:
- parabens
- TEA (triethanolamine)
- fragrance (phthalates)
- sodium lauryl/laureth sulphate (SLES)
- triclosan
3. Eat organic produce, pastured meat/dairy.
4. Make their own cleaning products from household vinegar, baking soda, or tea tree oil or purchase similarly simple products.
5. Avoid eating or drinking from heated plastics.
6. Avoid cell phone use.
7. Avoid processed foods and sugar.
8. Consume low-mercury fish (e.g., cod, salmon, sardines, shrimp, sole).
9. Carefully consider the risks and benefits of any elective medical interventions.
Our most important interface between self and the environment is the gut.
The vagus nerve appears to be the primary conduit between the 200 to 600 million nerve cells in our enteric or intestinal nervous system and our central nervous system.
Stimulation and function of these cells is directly affected by the population of bacteria that:
- nourish the enterocytes
- promote immune tolerance
- alert us of danger
Our intestinal microbiome is determined by:
- our mode of birth delivery (C-section/Cesarean birth vs. vaginal birth)
- whether we were breastfed
- early exposures through environment and diet
Nonetheless, intestinal microbiome can ever be modifiable through:
- macronutrients (carbohydrates, fat, protein)
- micronutrients (vitamins and minerals)
- stress
- supplementation
In fact, clinical investigation into the beneficial effects of probiotics (Lactobacillus and Bifidobacterium) on mood and anxiety have suggested that probiotics may promote anti-inflammatory responses through IL-10 (Interleukin 10) activation and alleviate anxiety.
An area of innovative speculation is looking at the role of melatonin as a treatment intervention in the third trimester and postpartum.
If serotonin is compromised by inflammation or dietary insufficiency of tryptophan, melatonin will be as well.
Melatonin plays a pivotal role in sleep onset and maintenance, but perhaps of equal importance, as a powerful antioxidant line of defense.
Tryptophan has been studied in the general population as an antidepressant and augmentation strategy with sleep-promoting and anxiolytic properties.
A study published in 1999 by the journal Biological Psychiatry, with Susanne Steinberg, M.D., as lead author, investigated its efficacy for hormonally related pathology in luteal phase dysphoria. The study suggests that tryptophan may have a role in postpartum states of progesterone suppression.
As it relates to the kynurenine catabolism pathway, it has also been noted that women with depression and anxiety in early puerperium (postpartum period) have higher kynurenine-to-tryptophan ([Kyn]/[Trp]) ratios indicating tryptophan degradation secondary to inflammatory stimuli.
Omega-3 fatty acids come under the umbrella of essential polyunsaturated fatty acids, which refers to their dietary requirement and to their unique carbon/hydrogen structure.
The best-studied representatives are docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).
EPA is a relatively minor structural component of nerve cell membranes influencing fluidity but a major prostaglandin precursor, whereas DHA is a primary component of brain grey matter.
Humans are assumed to be relatively inefficient at converting essential linoleic acid and alpha-linolenic acid precursors into highly unsaturated fats and eicosanoids, such as the omega-6 fatty acids - dihomo-gamma-linolenic acid (DGLA) and arachidonic acid (AA) - and the omega-3 fatty acid, EPA, which is derived primarily from fish and pastured meat.
A high-carbohydrate diet and associated elevation in insulin and glucose levels may upregulate phospholipase A2, which cleaves fatty acids from phospholipids, disturbing membrane structure.
Given the prevalence of refined vegetable oils in the American diet, some researchers posit that omega-6 fatty acids dominate dietary sources of omega-3s (a point of question is whether these vegetable oils in commercial foods represent trans or distorted fats when incorporated into human phospholipids).
The anti-inflammatory effect of omega-3 fatty acids may be related to their interference with key inflammatory cytokines and competitive inhibition of the cyclo-oxygenase pathway, but there may also be a role in:
- neurotrophic growth
- genetic expression
- neurotransmitter production and function
Currently, the only means of assessing individual fatty acid needs is through erythrocyte analysis, and the optimal dietary omega-6-to-omega-3 ratio ranges from 4:1 to 1:1, depending on the source consulted.
Disparity in benefit with omega-3 supplementation may relate to a lack of individual assessment for need.
There is a risk that chronic oversupplementation of omega-3 from flax and/or fish oil may impair the production of omega-6 highly unsaturated fatty acids and contribute to imbalance through competitive inhibition of desaturase enzymes.
Those fatty acids include:
- gamma linolenic acid (GLA)
- DGLA (dihomo-gamma-linolenic acid)
- arachidonic acid or AA (precursors to prostaglandin E1 or PGE1 and prostacyclin)
The effect of GLA administration can be simplistically attributed to structural membrane support and production of eicosanoid DGLA, which serves to regulate AA (promoting its retention in the membrane) through its conversion to PGE1.
At least three randomized, placebo-controlled trials of evening primrose oil (0.5 to 2 mg.) in premenstrual syndrome suggest that GLA is an effective intervention potentially related to its potentiation of PGE1 and attenuation of prolactin sensitivity at the receptor site in the membrane.
The importance of individual biochemical profile is an essential consideration.
Epidemiologic data suggest that prevalence of perinatal depression is inversely associated with fish consumption and breast milk levels of DHA.
In the postpartum period, there is concern for the maternal reservoir of essential nutrients having been largely depleted by the needs of growing fetus. Without appropriate repletion, these deficits may represent an underlying etiology of postpartum depression and anxiety.
Immediately following delivery, omega-3 fatty acids are lower and omega-6-to-omega-3 ratios higher in women who develop depressive symptoms at 6 to 10 months postpartum.
One study demonstrated that recovery of maternal DHA levels at 32 weeks postpartum was slower in women with postpartum depressive symptoms, potentially reflecting reduced membrane fluidity.
A prospective cohort study demonstrated that women with dietary ratios of omega-6-to-omega-3 fats greater than 9:1 (unclear whether adequate control for trans-fat intake) had a higher incidence of postpartum depression as assessed by the Edinburgh Postnatal Depression Scale (EPDS).
Given concerns over pollutants and mercury contamination of marine sources, many patients may benefit from considering a molecularly distilled, third-party-checked supplement.
Folate (B9) is found in leafy greens, lentils, broccoli, and sunflower seeds and is an important cofactor in the:
- synthesis of monoamines
- reduction of homocysteine
- slowing brain breakdown of tryptophan
The relationship between folate and depression has been explored in studies linking low serum levels to:
- poor treatment response
- elevated homocysteine
- depression incidence and augmentation
- increased likelihood of remission
There are four transformation steps required to render folic acid a biologically available form of folate that can cross the blood-brain barrier to participate in the production of neurochemicals.
One of these metabolites, 5-MTHF (5-methyltetrahydrofolate) or L-methylfolate, is required for the production of biopterin, a cofactor for neurotransmitter production, and of methionine/S-Adenosyl-L-Methionine (SAMe) from homocysteine (with B12 as a cofactor), influencing the production and function of neurotransmitters, DNA and enzymes.
Recent literature has focused on the role of genetic polymorphism for MTHFR (methylenetetrahydrofolate reductase) in the metabolism of folate and associations with depressive illness.
For individuals with variants in one of the two known genes, C677T, and 1298C, efficiency of conversion of folate or folic acid to L-methylfolate is compromised to varying extents.
Maternal MTHFR polymorphisms are associated with antenatal depression and may influence the fetal programming of serotonin transporter methylation and future functioning.
A study in the postpartum population published in 2012 by the European Journal of Clinical Nutrition, with Sarah J. Lewis as lead author, demonstrated benefit with regard to EPDS scores at 21 months postpartum for women with C677T polymorphism who supplemented with folic acid during pregnancy.
Bypassing this enzymatic conversion with supplementation of bioactive folate appears to be a potentially important treatment option.
Thus, it is important to assess individual risk factors in termsof dietary/supplement intake in the first trimester and biomarkers for methylation. Taking the multiple potential pathways to postpartum depression and anxiety into account, the multi-modal effects of curcumin, the principal curcuminoid of the Indian spice turmeric, are very appealing.
Some of those potential pathways to postpartum depression and anxiety include:
- hypothalamic-pituitary-adrenal (HPA) axis
- dysregulated inflammatory pathways
- increased oxidative stress
- mitochondrial dysfunction
- nutrient depletion
Although much of the data are animal-based at this point, curcumin has demonstrated anti-inflammatory modulation of cytokines, including COX-2 (cyclooxygenase-2) inhibition, and inhibition of IDO (indoleamine 2,3-dioxygenase) expression, neurotransmitter-supportive through monoamine oxidase (MAO) inhibition mechanisms, and protective against oxidative stress on a mitochondrial and tissue level.
When used as a culinary spice or as a concentrated curcumin supplement, absorption is enhanced with pepper.
The picture below shows the mechanisms of action of curcumin:
A diagram with an arrow in the middle moving clock-wise and forming a big circle and the word ‘curcumin’ inside it Cranial electrical stimulators are FDA-approved patient-administered devices. They are indicated for the treatment of:
A low-intensity alternating current is transmitted across the skull for 20 minutes once or twice daily to promote alpha-wave activity and to modulate:
- neurotransmitters
- endorphins
- cortisol
The five meta-analyses include 67 human studies (n = 2,910) and demonstrate the efficacy of devices without report of adverse events.
There are no perinatal studies of the device; however, given the relative safety of electroconvulsive treatments in the pregnant population, adverse effects are unlikely.
This device may represent a first-line option for women, given that it is non-invasive with a low-side-effect profile.
Perhaps the most potent healthelixir, exercise is never more important than in our sedentary, technology-driven societies. It has been demonstrated to have resonant clinical benefits, such as those evidenced by a controlled trial that looked at 3 hours of weekly exercise in depressed postpartum women and found that they improved significantly relative to controls.
Perhaps one of the putative mechanisms of this improvement is the effect of exercise on inflammatory cytokines, such as those demonstrated in the Treatment with Exercise Augmentation for Depression (TREAD) study, where depressed patients, partially treated with an antidepressant, were found to have clinical improvement that correlated with decrease in THF-alpha.
As was demonstrated in a pilot study looking at mindfulness-based yoga practice in an antenatally depressed population, interventions that are based on ancient practices of parasympathetic nervous system support may also present a feasible option for non-medication treatment.
The practice of yoga has been demonstrated in the general and chronically ill population to have a favorable impact (in as short a time as 10 days) on:
- cortisol
- endorphins
- inflammatory cytokines (such as IL6 and TNF-alpha)
A study published in 2013 by the journal PLoS One, with Manoj K. Bhasin as lead author, examined the immediate and long-term epigenetic effects of meditation finding that within 15 minutes of relaxation response practice, genomic benefits were apparent at centers thought to be responsible for:
- inflammatory control (downregulation of nuclear factor kappa B or NF-KB)
- insulin release
- mitochondrial function
It is now appreciated that sciencehas not been able to replicate the complexity of breast milk and the myriad essential benefits it confers to an infant and baby and that formula feeding may have negative repercussions for the mother as well. An interesting exploration of this topic discusses the protective effect on mother’s mood and perceptions of stress when breastfeeding as well as the attenuation of cortisol in response to stressors during suckling.
Immune support is conferred to mother and baby during exclusive breastfeeding.
A concern related to the aforementioned toxic exposures is the accumulation of environmental contaminants in breast milk.
Chlorella, a type of freshwater algae, has been studied as a means of promoting excretion of environmental dioxin exposure and enhancement of immune support through elevated levels of IgA (immunoglobulin A) and may represent a low-risk intervention when exposures are suspected.
Although exercise, relaxation response, and targeted supplementation of the postpartum patient with anti-inflammatory nutrients have not been formally studied, they hold promise for low-risk, potentially high-yield interventions of benefit to the mother and the infant.
Some anti-inflammatory nutrients include:
- turmeric
- probiotics
- folate
- omega-3s
- melatonin
Promoting immune system balance through minimization of lifestyle-related sources of inflammation represents a powerful common sense tool for health and wellness in the reproductive years and beyond.
Such sources of inflammation include:
- sugar
- trans fats
- stress
- poor sleep
- sedentariness
- toxic chemical exposures
For the patient at risk for postpartum depression (based on personal, family history, or socio-demographics), implementation of lifestyle modification as prophylaxis would be beneficial. In the setting of active symptoms, the patient who elects not to take psychiatric medication should be offered alternatives in addition to psychotherapy and group support.
In the end, more studies should be conducted about neuroinflammatory models of postpartum depression to broaden our knowledge about them.